I’m experiencing a noticeable jerking or lunging sensation when my 2004 Clk 320 Mercedes shifts from first to second gear. This issue, common among other owners, has become more pronounced recently. While downshifts seem smoother, I’ve detected a subtle slipping feeling at higher speeds, particularly when using cruise control.
Hoping a fluid and filter change would alleviate the problem, I took my car to a trusted local mechanic specializing in Mercedes-Benz and BMW vehicles. During the service, we found metal particles in the transmission filter and on the magnet – described as a significant amount. The drained fluid was dark and had a burnt odor, although there was no sign of coolant contamination. Based on these findings, the mechanic suggested that a used or rebuilt transmission might be necessary.
Before committing to a transmission replacement, I decided to investigate further. I researched online forums and inspected the Transmission Control Unit (TCU) located in the passenger footwell. I found transmission fluid on the wiring harness, indicating a potential leak. I proceeded to clean the TCU and its connectors with electronic cleaner, noticing a slight brown discoloration on the connector pins. Despite reinstalling the cleaned TCU and attempting a transmission reset procedure (key in ‘on’ position, accelerator pedal to the floor), the jerking issue persists during the 1-2 shift.
Considering the symptoms and the mechanic’s initial assessment, I’m seeking advice on other potential causes or diagnostic steps to explore before considering a full transmission replacement for my 2004 CLK 320 Mercedes. Could a faulty TCU still be the culprit even after cleaning? Would a software update from a Mercedes-Benz dealer be beneficial in this situation? Any guidance or insights would be greatly appreciated as I navigate this 2004 CLK 320 Mercedes transmission concern.
